Starting with a Blank VI

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Table of Contents >Quanser Rapid Control Prototyping Toolkit >Getting Started >Creating a New VI >

Since the RCP Toolkit uses a minimal set of VIs to access hardware and other operations, it is easy to create a new VI from scratch that uses the RCP Toolkit. To begin with, create a blank via by selecting File/New VI from the LabVIEW or project menu, as illustrated below. If using a project, be sure to select the My Computer section.

File/New VI menu

Right-click in the block diagram and select the Control & Simulation Loop from the Control Design & Simulation palette.

Creating a Control Design & Simulation Loop

Click in the block diagram and drag the mouse to form a rectangle the size of the loop that you want. Release the mouse to place the Control Design & Simulation Loop in the diagram with the chosen size.

Double-click on the left input to the Control Design & Simulation Loop or right-click on the border of the loop and select Configure Simulation Parameters... from the context menu:

Configure Simulation Parameters menu

The Configure Simulation Parameters dialog will open. On the Simulation Parameters tab, set the parameters as follows:

Parameter Name	Parameter Value
Final Time	Inf
ODE Solver	Runge-Kutta 1 (Euler)
Step Size (s)	0.002
Auto Discrete Time	Checked

The final settings on the Simulation Parameters tab should look like this:

Simulation Parameters tab

Other values for the solver and step size may be chosen, but a fixed-step solver should be used. A step size of 2ms is usually a good starting point for many control systems and should be achievable on both Windows and the CompactRIO.

On the Timing Parameters tab, set the parameters as follows:

Parameter Name	Parameter Value
Synchronize Loop to Timing Source	checked
Auto Period	checked

The final settings on the Timing Parameters tab should look like this:

Timing Parameters tab

Click OK to save the settings.

To access hardware using the RCP Toolkit, a HIL Initialize VI is required. Right-click to the left of the Control Design & Simulation Loop in the diagram and choose the HIL Initialize VI from the Quanser Rapid Control Prototyping palette, as depicted below:

Adding a HIL Initialize VI

After placing the HIL Initialize VI in the diagram, double-click on it and choose the data acquisition card you intend to use. For example, select the Q2-USB as shown below:

HIL Initialize parameters with Q2-USB selected

Click OK to save the changes. Wire the error out terminal of the HIL Initialize VI to the Error input terminal of the Control Design & Simulation Loop. Also wire the board out terminal to the edge of the loop. Finally, create an error indicator at the output of the Control Design & Simulation Loop as shown:

HIL Initialize wiring

Warning

Always wire the output of the Control Design & Simulation Loop to an error indicator. Do not depend on automatic error handling to report errors because the error dialog interrupts the execution of the VI. Interrupting a running control system is dangerous, so automatic error handling must be avoided. Quanser recommends adding a HIL Watchdog VI to the loop as well if the hardware supports it to ensure hardware outputs are reset to zero in such instances.

The VI is now ready for hardware access. Use the CL HIL Read and CL HIL Write VIs in the Quanser Rapid Control Prototyping/Immediate I/O palette for single sample reads and writes from any or all channels of the data acquisition card.

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